(4-Hydroxyphenoxy)alkane derivatives such as, for example, alkyl 2-(4-hydroxyphenoxy)propionates, are useful intermediates for the synthesis of a wide range of (aryloxyphenoxy)alkane derivatives which have been shown to have herbicidal activity. In the past the required (4-hydroxyphenoxy)alkane derivatives have been prepared either:
(i) by condensing the appropriate 4-alkoxyphenol with the appropriate alkane derivative to give a (4-alkoxyphenoxy)alkane derivative and then cleaving the alkyl residue from the 4-alkoxy group; or PA0 (ii) by condensing the appropriate hydroquinone with the appropriate alkane derivative. PA0 (a) reacting a sulfate ester of formula II, ##STR7## wherein Q is a cation, with a compound of formula PA0 (i) oxidizing a compound of formula IV ##STR9## with persulfuric acid or a salt thereof to form a sulfate ester of formula II, ##STR10## wherein Q is a cation; and (ii) which process is characterized by the following steps in sequence: PA0 (a) reacting a 4-hydroxyphenylsulfate salt with a 2-halopropionic acid or a derivative thereof; and PA0 (b) hydrolysing the sulfate ester formed in step a) to give the 2-(4-hydroxyphenoxy)propionate. PA0 (a) reacting the 4-hydroxyphenylsulfate salt with a 2-halopropionic acid or a derivative thereof; and PA0 (b) hydrolysing the sulfate ester formed in step (a) to give the 2-(4-hydroxyphenoxy)propionate.
However, both of these processes suffer the disadvantage advantage of using relatively expensive hydroquinone (derivatives) and the first process suffers the additional disadvantage of requiring the use of relatively expensive reagents to cleave the alkyl residue from the 4-alkoxy group.